630 ECOLOGY AND BEHAVIOR 



increases following ACTH administration (Payan and Maetz 1971). Increased 

 sodium chloride and /or water retention could also be due to decreased 

 secretion of the rectal gland, functional impairment of the kidneys, or 

 decreased sodium excretion at the gills. The interrenal organ is active over 

 the period of starvation (see above); its secretions are powerful mineral- 

 ocorticoids (Idler, Freeman, and Truscott 1967), and the rectal gland has 

 been shown to be responsive to corticoid administration (Chan and Phillips 

 1967). 



The rise in serum potassium is attributed to two sources: (a) an increased 

 catabolism of tissue proteins with concommitant leakage of intracellular 

 potassium and (b) an increase in intravascular hemolysis. A tendency to 

 hemolyze was observed in the studies of Hartman et al. (1941, 1944) but not 

 in those of Idler and Szeplaki (1968). In the present study, rising chloride 

 levels were often accompanied by rising concentrations of serum iron, and 

 the highest potassium values were observed in conjunction with elevated 

 chloride and iron levels. All the observed increases in serum potassium, 

 chloride, and iron are not attributed to hemolysis, however, for on several 

 occasions each increased independently. 



The alterations in ionic components observed during the period of 

 starvation thus include increases in serum sodium, calcium, iron, potassium, 

 and chloride. 



Metabolic Alterations 



The levels of total serum lipids reported here for 16 freshly caught animals, 

 averaging 809 mg%, agree with figures for Squalus reported by Lauter, 

 Brown, and Trams (1968) of 792 mg%. Sargent et al. (1971) found much 

 lower lipid levels (125 mg%) in the blood of fasting male Squalus; valid 

 comparison with the present study is difficult because the animals were both 

 smaller (1.5 kg vs 3-5 kg) and of the opposite sex. Variation in the lipid 

 content of the serum may exist in the population as a function of the 

 reproductive state of the individuals. The highest lipid levels recorded were 

 found in three freshly caught animals possessing flaccid uteri, which had 

 presumably pupped immediately before capture. These animals had very 

 large ovarian ova. A marked decrease in serum lipid was observed in all 

 animals over the experimental period; much of the decline may represent a 

 decrease in mobilization and transport of lipid components required for the 

 maturation of oocytes. A decrease in gonadotrophin levels is common during 

 starvation in mammals (Dill, Adolph, and Wilber 1964), and atrophy of 

 gonadal tissues follows prolonged adrenocortical activity (Moon 1961). 

 Davydova (1972) has described a cessation of oocyte development during 

 starvation in captive sturgeon, and Rasquin and Atz (1952) reported 

 regressive changes in the gonads of Astyanax mexicanus treated with ACTH 

 or cortisone. Low levels of lipid in the serum of females starved in the 

 present study approximate serum lipid levels of starved male Squalus 

 reported above (Sargent et al. 1971). 



In mammals, which rely principally upon lipid metabolism during periods 



